Process for insitu treatment of soil and groundwater

ABSTRACT

A process for insitu treatment of at least one contaminant in groundwater, the process comprises the steps of: installing a permeable reactive barrier in the flow path of the at least one contaminant, wherein the installation of the permeable reactive barrier comprises the steps of: boring a first borehole with a portion longitudinally extending; filling the longitudinally extending portion with a reactive material comprising a solid reactant configured to react with the at least one contaminant in the groundwater to produce at least one product having less hazardous characteristics than the at least one contaminant; boring a second longitudinally extending portion and filling the second longitudinally extending portion with the reactive material.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Utility patent applicationSer. No. 13/478,937, filed May 23, 2012, and which application is herebyincorporated by reference in its entirety.

FIELD OF INVENTION

The present invention relates to methods for insitu treatment of soiland groundwater, more specifically towards methods of treatmentincluding permeable reactive barriers and solid reactants.

BACKGROUND OF THE INVENTION

Discharges of hazardous organic compounds into the environment have ledto contamination of surface water, soil, and aquifers resulting inpotential public health problems and degradation of the land for futureuse. As used in this specification and appended claims, hazardousorganic compound means a chemical or substance that is either toxic orhighly toxic, an irritant, corrosive, a strong oxidizer, a strongreducer, a strong sensitizer, combustible, either flammable or extremelyflammable, dangerously reactive, pyrophoric, pressure-generating, acompressed gas, a carcinogen, a teratogen, a mutagen, a reproductivetoxic agent, or is suspected of having adverse health effects on humans.In many cases, subsurface groundwater contaminant plumes may extendhundreds to thousands of feet from the source area of a chemical releaseresulting in extensive contamination. These chemical contaminants maythen be transported into drinking water sources, lakes, rivers, and evenbasements of homes.

The U.S. Environmental Protection Agency (USEPA) has established maximumconcentration limits (MCL's) for various hazardous organic and inorganiccompounds in water and soils. For instance, stringent drinking waterlimits placed on many solvent organic compounds in water can be as lowas 0.005 mg/L (parts per billion).

The presence of hazardous compounds in subsurface soils, surface water,and groundwater is a well-documented and extensive problem. The sourceof these hazardous materials is often times from industry where thematerials are released onto the soil surface or surface water or eveninto the subsurface soil and/or groundwater through leaking storagetanks. Many, if not most, of these compounds are capable of movingthrough the soil under the influence of moving water, gravity, orcapillary action and serve as a source of groundwater contamination. Asused in this specification and appended claims, soil is to beinterpreted broadly to include all naturally occurring material foundbelow ground surface (e.g. silts, clays, sands, rock, karsts, organics,tills, etc.).

Soil, surface water, groundwater, and wastewater can become contaminatedby a variety of substances. The substances include, without limitation,metals, volatile, semi-volatile, and non-volatile organic compounds.Common examples of such contaminates include arsenic, barium, cadmium,chromium, lead, mercury, selenium, silver, PCBs, gasoline, oils, woodpreservative wastes, and other hazardous organic compounds. Such otherhazardous organic compounds may include, but not limited to, chlorinatedsolvents (such as trichloroethylene (TCE), vinyl chloride,tetrachloroethylene (PCE), and dichloroethanes), ethylene dibromide,halobenzenes, polychlorinated biphenyls, acetone, ter-butyl alcohol,tert-butyl formate, and anilines. Additional contaminants includecompounds containing at least one oxidizable aliphatic or aromaticcompound and/or functional group (e.g. atrazine, benzene, butylmercaptan, chlorobenzene, chloroethylvinyl ether, chloromethyl methylether, chlorophenol, chrysene, cyanide ion or organic cyanides,dichlorophenol, dichlorobenzene, dichloroethane, dichloroethene,dichloropropane, dichloropropene, ethyl alcohol, ethylbenzene, ethyleneglycol, ethyl mercaptan, hydrogen sulfide, isopropyl alcohol, Lindane™,methylene chloride, methyl tert-butyl ether, naphthalene, nitrobenzene,nitrophenol, pentachlorophenol, phenanthrene, phenol, propylene,propylene glycol, Silvex™, Simazine™, sodium sulfide, tetrachloroethane,tetrachloroethene, toluene, trichlorobenzene, trichloroethane,trichloroethene, trichlorophenol, vinyl chloride, xylene, etc).

Contaminated soil and groundwater must be removed or treated to make itless toxic and to meet USEPA requirements. There are a variety ofreactants and methods for treating contaminated soil, surface water,groundwater, and wastewater as discussed below.

Peroxydisulfate's have been reported as applied constituents for organiccarbon digestion or decomposition. Application methods include thermallyactivated persulfate oxidation in conjunction with an electro-osmosissystem to heat and transport persulfate anions into soils.

Permanganate(s) and peroxygen(s) reactant(s) have also been reported asapplied constituents for oxidation of organic compounds. Peroxygencompound(s) applied independently or in conjunction with a metallic saltcatalyst(s) (complexed and not complexed; chelated and not chelated)have been shown to break down organic compounds within the soil,groundwater, and wastewater.

Groundwater and subsurface soil typically has been treated by injectingreactant(s), with or without a catalyst(s), within an aqueous mixture,slurry, or suspension into the subsurface. Injection into the subsurfaceis accomplished by gravity feed or the use of a pump(s) to increase wellhead pressure. This results in the subsurface dispersion of thereactant(s) within the area of the injection well.

Another method for in situ treatment of groundwater includes theexcavation of a trench proximate or downstream of a subsurface plume oforganic and/or inorganic contaminant(s). The trench is filled withreactant(s) and a permeable media(s) (i.e. sand) for the plume to flowthrough, subsequently reacting oxidizable and/or reducable organicand/or inorganic compounds that come into contact with the reactant(s).These trenches filled with a reactant are often referred to as permeablereactive barriers (PRBs). One limiting factor in current methods ofinstalling PRBs is that structures, roads, or other improvements to theland above the installation site may need to be destroyed when diggingthe trench. Alternatively, the trench may need to be located furtherdown flow of the plume of contamination than desired, to avoiddestruction of improvements to the land nearer the plume ofcontamination. Other limiting factors may include a requirement forheavy equipment and the need to move the heavy equipment across the landto excavate the trench which may be destructive or detrimental to theground. Additionally, current methods for installing PRBs may requiredisposal of large volumes of cuttings or soils removed to form a trench.These removed cuttings or soils may be hazardous which may increasehealth and safety requirements and disposal costs.

The methods used for ex situ treatment or in situ treatment of surfacecontamination, water or soil, typically involve the direct applicationof the reactant(s) to the hazardous organic compound(s). In the case ofex situ surface soil treatment, the soil is often times mixed or tilledto ensure contact of the reactant(s) with the hazardous organiccompound(s).

Meeting USEPA cleanup criteria with these reactants and methods of theprior art has been found to be difficult, costly, and even impossible.With some of these current methods and reactants, there has beenquestionable showing that their application results in the effective orefficient removal of contaminants.

Current methods involving the use of peroxide group(s) (i.e. hydrogenperoxide) in conjunction with iron salt catalyst(s) have shown to berelatively inefficient, often resulting in incomplete contaminantoxidation. Hydrogen peroxide in particular has been found to lackpersistence in contaminated soils and groundwater due to rapiddissociation. Many of these current employed reactants are hazardous anddifficult to handle.

Recently, the use of permanganate(s) has been found to be an effectiveoxidizing agent of certain hazardous organic compound(s). However, knownmethods to use that ability to actually remediate a site requiresexceedingly large quantities of permanganate(s) to overcome the naturaloxidant demand exerted by the soil, thereby limiting the percentageavailable for oxidizing the hazardous organic compound(s). Large amountsof permanganate(s) may thus be required per unit of soil and groundwatervolume, limiting the application of this technology due to high cost.Additionally, a product of the permanganate(s) oxidation reaction issolid manganese dioxide, which may precipitate and clog the soil oraquifer, resulting in a reduced permeability of the soil to water. Thisclogging may reduce the hydraulic conductivity of the soil and therebyinhibit oxidant access to the entire contaminated site, renderingtreatment of the soil and the groundwater plume flowing therethrough,incomplete.

Because of these limitations of the art before the present invention,there is a need for improved methods of insitu treatment of soil andgroundwater contamination.

SUMMARY OF THE INVENTION

One aspect of the present disclosure provides a process for insitutreatment of at least one contaminant in a groundwater plume comprisingthe steps of: 1) installing a permeable reactive barrier in the flowpath of the groundwater plume, wherein the installation of the permeablereactive barrier comprises the steps of: a) boring a first borehole witha portion longitudinally extending substantially parallel with an uppersurface of the groundwater plume; b) filling the longitudinallyextending portion of the first borehole with a reactive materialcomprising a solid reactant configured to react with the at least onecontaminant in the groundwater plume to produce at least one producthaving less hazardous characteristics than the at least one contaminant;c) boring a second borehole with a portion substantially adjacent oroverlapping the longitudinally extending portion of the first borehole;and d) filling the portion of the second borehole substantially adjacentthe longitudinally extending portion of the first borehole with thereactive material; 2) passing at least a portion of the groundwaterplume having the at least one contaminant through a portion of thepermeable reactive barrier; and 3) reacting at least a portion of the atleast one contaminant with a portion of the permeable reactive barrierto produce at least one product having less hazardous characteristicsthan the at least one contaminant.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a PRB installed by the methoddisclosed herein;

FIG. 2A is a side view of a duckbill drill head; and

FIG. 2B is a side view of a rotary drill head.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a method for the insitu treatment ofcontaminated groundwater and soil with solid environmental reactant(s).

Aspects of the present disclosure provide a method for the installationof PRBs without the need for trenching. Directional boring may be usedwhen trenching or excavating is not practical or cost effective. Forexample, when there are improvements to the land above the leading edgeof a contaminated groundwater plume it may be advantageous to install aPRB with directional drilling rather than trenching. Directional boring,directional drilling, or horizontal directional drilling (HDD), mayminimize disruption to the surface environment since no open trench iscreated and heavy equipment may not be required to move across the land.A directional drill may be suitable for a variety of soil conditions andjobs including installing a PRB under a road or structure. Boreholes inexcess of a mile long may be installed and/or diameters up to 56 inchesmay be obtained.

Directional boring, commonly called horizontal directional drilling orHDD, is a steerable trenchless method of making a borehole. Directionaldrilling is commonly used for the installation of underground pipes,conduits and cables. Typically, the borehole is in the form of a shallowarc proximate a prescribed bore path. A surface launched drilling rig,with minimal impact on the surrounding area, may be used. For example,horizontal directional drills manufactured by Vermeer of Pella, Iowa,and directional drills manufactured by DitchWitch® of Perry, Okla., maybe used for the installation of PRBs of the instant disclosure.

The use of directional drilling methods for the installation of PRBs mayprovide less traffic disruption, lower cost, deeper and/or longerinstallation, shorter completion times, directional capabilities, andincreased environmental safety, and less hazardous waste produced fordisposal, as compared to current trenching methods. Additionally, in atleast one embodiment of the present disclosure, no access pit isrequired as the directional drill rig may be placed on the soil surface.In another aspect of the present disclosure, a small access pit andreceiving pit may be provided.

The installation of a borehole for the installation of a PRB may includeseveral steps with a first step including drilling a first hole or pilothole on the desired path, which may have a portion proximate an upper orlower surface of the groundwater table, just down flow of a plume ofcontamination. A second step of enlarging the borehole by passing alarger cutting tool or back reamer through the pilot hole may be takenif the pilot or first hole lacks the desired diameter. A third step mayinclude placing or inserting a tube or pipe configured to permit flow ofwater through a circumferential surface thereof. The tube or pipe may beporous or otherwise permeable, such as tubing or pipe havingperforations, slots, or other openings therein configured to provide theflow of water through the side of the tubes or pipes. The tubes or pipesmay be comprised of materials such as PVC, HDPE, polyethylene, ductileiron, copper, and steel. Advantageously, the tubes or pipes may beflexible, bendable or malleable so that they can be inserted into acurved borehole. Optionally, a tube or pipe may comprise a solidreactant therein. The tubes or pipes may be pulled or pushed into theborehole. A fourth step may comprise placing a solid reactant into thepermeable pipe or borehole. In some aspects of the present disclosure,the second step of enlarging the borehole and/or the third step ofplacing a permeable pipe into the borehole may not be necessary. Thismay be because the first borehole may have a desired diameter and/or thesolid reactant may maintain the integrity of the borehole or perhaps theborehole may be permitted to collapse. For example, the reactant may beplaced directly into the borehole without a tube or pipe. Additionally,the reactant may be fed into the borehole during drilling or afterdrilling the borehole.

The directional control capabilities of directional drilling may providefor making changes in the directions of the drilling head. For example,a pilot borehole may be made by starting perpendicular to the surface,at 45° with the surface, at 30° with the surface, or at another desiredangle with the surface, and curved or arced to a desired angle,typically substantially parallel with the groundwater table.

Several means may be used in directing the boreholes during drilling orboring. For example, a sonde or transmitter may be located behind thebore head or drill bit and configured to register angle, rotation,direction and temperature data, for example. This information may thenbe encoded into an electro-magnetic signal and transmitted through theground to the surface in a walk-over system. At the surface a receiver(usually a hand-held ‘locator’) may be manually positioned over thesonde, the signal decoded and steering directions may then be relayed toa bore machine operator. In a wireline system, this information may betransmitted through a cable fitted within the drill string.

The directional drilling rig may be set in a bore pit or up on theground surface. A pilot borehole may be started by pushing a drill rodthrough the ground at a shallow angle such as 45°, 30°, 20°, 10°, orsteeper or shallower, in one degree increments such as approximately12°. When the drill head reaches the desired depth, the bore head may besteered along a sag shaped curve or arc until it levels out. This maybegin a portion of the borehole that longitudinally extends substantialparallel with an upper surface of the groundwater plume. Upon obtainingthe desired angle of the borehole, drilling or boring may be continued,typically substantially parallel with an upper surface of thegroundwater plume, until the desired length is achieved, e.g. thedesired length of the PRB. Upon reaching the desired length, the drillhead may be extracted by backing out of the borehole or steered to areceiving pit. Optionally, the drill head may be steered upward througha sag shaped curve to exit the ground at the surface.

Directional drilling is a boring method which can be remotely steered.This may be accomplished through the use of a slanted, or anvil shapeddevice, often called a duckbill. The duckbill attaches to the front ofthe drill head. The angle of the duckbill causes the drill head to movealong a curved path. In order to change the direction of the bore, thedrill stem and duckbill may be rotated to a position causing the bore tomove in the desired direction. To bore in a straight line, the drillstem and duckbill may be rotated continuously as the bore is advanced.For larger diameter bores, the duckbill may be replaced with a sectionof slightly bent or curved pipe called a bent sub. A bent sub typicallycomprises a short cylinder installed in the drill stem between thelowest drill collar and the downhole drill head and is configured todeflect the drill head from vertical in order to drill a directionalhole. The bent sub may provide the same purpose and effect as theduckbill.

In order to steer a bore around obstacles or form a desired shape of thePRB, the operator must know the location of the borehead and thedirection it is traveling. This information is provided through thevarious tracking systems that are available. The most common method is a“walk-over” system. A radio transmitter or “sonde” is located directlybehind the bore head and transmits a signal. A receiver, similar tothose used by utility companies to detect underground pipes or cables,may be used to determine the location and depth of the borehead. Thedrawback of the walkover system is that it may be difficult to gainaccess to the area directly above the bore head (i.e. for watercrossings, or bores under buildings). There are also “hardwire” trackingsystems available. These systems relay information such as headlocation, depth, and inclination and orientation of the head back to acomputer. Based upon this information, the operator can make anynecessary adjustments to keep the bore on the desired alignment. Forsmall diameter bores, the reactant or slurry containing the reactant maybe fed into the borehole while retracting the bore head or afterretracting the bore head from the borehole. Optionally, a tube or pipecontaining a reactant and configured to permit flow of water through acircumferential surface thereof, may be pulled back through the pilothole with no additional enlargement of the hole required.

If a larger diameter borehole is desired, the pilot hole may be backreamed. Back reaming may be accomplished by removing the drill head andattaching a back reamer to the drill string. The back reamer serves twofunctions. The first and most obvious is to enlarge the diameter of theborehole to a desired size. The size of the borehole may be larger thanthe diameter of a slotted or perforated tube or pipe to be installed,such as about 1½ times the diameter of the tube. The second function ofthe reamer is to mix the soil cuttings with the drilling fluids tocreate a slurry. The reamer is rotated and pulled back through the pilothole, thereby cutting the soil and increasing the diameter of the bore.At the same time, drilling fluid is pumped through the drill string tothe reamer. The cuttings mix with the drilling fluid, forming a slurry.Some of this slurry may be forced out of the bore hole, into a receivingpit. However, most of the slurry may remain in place to support theborehole, and keep it from collapsing. A reactant may be added to theslurry, advantageously upon reaching a desired diameter, and forced intothe borehole. Optionally, a slotted, perforated, screened, or otherwisepermeable tube or pipe may be laid out in-line with the bore and pulledinto place. As it is pulled into place, a volume of slurry may be forcedout of the borehole. A volume of slurry may remain between the outsideof the tube or pipe and the inside of the reamed borehole providingsupport to the borehole. The tube or pipe may be packed with a reactantor the reactant may be forced into the tube or pipe after installed intothe borehole.

In at least one embodiment of the present disclosure, pre-packed lengthsof porous tubing are joined together and fed into the borehole. Forexample, lengths of porous tubing packed with at least one solidreactant may be provided to aid in installation. The lengths of tubingor pipe may be flexible (e.g. corrugated drainage pipe) or inflexible.The lengths of tubing may have threaded ends for screwing together ormay be joined with a flexible coupling such as a Fernco boot,manufactured by Fernco Inc., Davison, Mich., for example. The lengths oftubing may be joined by other methods as are known in the art, such asplastic welding or fusing of HDPE. In at least one aspect of the presentdisclosure, lengths of pre-pack tubing are joined together upon feedingor inserting into the borehole. In another aspect, the lengths of tubingare not joined but may remain adjacent, end to end, in the borehole.

In at least one aspect of the present disclosure, pre-packed screened,sloted, or otherwise porous pipe may be pre-engineered with the correctwell screens, reactant size and concentration, and sand mix. Thepre-packed screened pipes may have relatively short lengths, such as 4-6feet, for example, such that they can be pulled back through theborehole and the end of one section of pipe may be attached to thebeginning of the next section in series. This may allow the packing anddesign of the porous or screened pipe to be done in advance. Thesepre-engineered lengths of tubing or pipe may provide for shorter lengthsof packed pipe that are easier to transport, handle, and install intothe boreholes.

The pilot borehole may also be enlarged by using slurry drillingmethods. Slurry methods may involve the use of a drilling fluid, such aswater or a slurry comprising clay based materials such as bentonite, forexample, to aid in the drilling process and soil removal. Slurry methodscan be divided into two classifications: slurry boring and waterjetting. Slurry boring normally begins by constructing a bore pit. Theboring machine is set in the pit and adjusted to the appropriate lineand grade. A pilot hole may be formed by the directional drillingmethods previously disclosed or by advancing drill tubing, with a drillbit attached to the end, through the ground. As the bit is advanced,drilling fluid is pumped through the tubing to the drill bit in order tolubricate the pilot drill and reduce the friction created by theadvancing bore. Once the pilot bore reaches the receiving pit, a backreamer can be pulled or a forward reamer can be pushed through theground to increase the bore to the required diameter.

As the reamer is forced through the ground, drilling fluid is pumpedinto the bore. Depending on soil type, this drilling fluid compriseswater and may further comprise one or more additives or other materialssuch as clay materials. For example, the drilling fluid may comprise amixture of water and bentonite. Optionally, the drilling fluid maycontain a reactant. The soil is mechanically cut by the reamer and mixedwith the drilling fluid. These cuttings are held in suspension forming aslurry. This slurry helps prevent the uncased borehole from collapsingby exerting hydrostatic pressure against the walls of the bore.

After the reaming process is completed, a reactant may be added to theslurry and forced into the borehole. Optionally, a slotted, perforated,or otherwise porous or permeable tube or pipe may be pulled into place.The tube or pipe may be packed with a reactant or the reactant may beforced into the tube or pipe after installed into the borehole. In atleast one aspect, pre-engineered lengths of porous pipe containing atleast one solid reactant are joined together upon installing into theboreholes.

Another method of forming a borehole is the water jetting method. Waterjetting relies on a high speed jet of water to liquify and remove soil.A special nozzle may be attached to the end of a rod and extendedforward into a pilot hole. Advantageously, a pilot borehole is firstmade with a directional drill as disclosed. The jet of high-pressurewater is used to perform all of the cutting and to wash the cuttings outof the bore.

Horizontal directional drilling may be done with a drilling fluid.Drilling fluid may be comprised of a mixture of water, polymer(s), claymaterial(s), such as bentonite, and/or other additives. The drillingfluid may comprise a solid reactant for inserting into the plurality ofboreholes to form the PRB. In this aspect of the present disclosure, thecompletion of the drilling step may be all that is needed to make aborehole having a reactant. The drilling fluid may be continuouslypumped to the cutting head or drill bit to facilitate the removal ofcuttings, stabilize the bore hole, cool the cutting head, lubricate thepassage of a porous tube or pipe, or deliver the solid reactant into theborehole.

Drilling fluids may be configured to stabilize the borehole, which maymitigate hydro-fracturing and allow a porous tube or porous tube packedwith solid reactant to be pulled-in more easily. The proper mix ofdrilling fluids may be determined by the soil conditions andcharacteristics of the water mixed with the drilling fluid and thereactant in the drilling fluid, if any. Geotechnical information may begathered in advance of boring and soils extracted from the borehole maybe tested periodically during the installation to verify that the properdrilling fluid mix and additives are being used as well as aconcentration of reactant in the fluid, if desired. Water may be checkedand adjusted for pH and the presence of calcium. Generally, drillingfluid, which carries soils from down-hole, should exit the hole at theentry or exit end of the installation. Drilling fluid flow providesvisual verification that the hole is open and that the fluids are notinadvertently escaping. Field tests that measure the drilling fluidsviscosity and weight can help determine the need to adjust drillingfluid mix and the rate at which a product can be safely installed.

Other methods of drilling, as are known by persons having ordinary skillin the art, may be used to install the PRB of the present disclosure. Inat least one embodiment of the present disclosure, a first borehole ismade with a portion longitudinally extending substantially parallel withan upper surface of a groundwater plume to be treated with a PRB. Asecond borehole is then made having a portion proximate, substantiallyadjacent or overlapping the longitudinally extending portion of thefirst bore hole. Advantageously, the first and second boreholes have aportion longitudinally extending substantially parallel with an uppersurface of a groundwater plume, substantially vertically aligned, andsubstantially adjacent with one another. Horizontal directional drillingmay provide for sufficient directional capabilities, but deviations froma desired direction or path are expected. Therefore, the termssubstantially parallel, substantially vertically aligned, andsubstantially adjacent mean that portions are parallel within acceptabletolerances, vertically aligned within acceptable tolerances, andadjacent within acceptable tolerances. Additional boreholes are made toform a plurality of substantially vertically aligned and substantiallyadjacent, or overlapping portions to form a PRB.

A slotted, perforated, porous, permeable, or otherwise configured topermit the flow of water through a circumferential wall, tube, casing,or pipe may then be pulled or otherwise inserted into the firstborehole. The tube or pipe may be inserted into a portion of theborehole having a desired angle and/or length, or desired portion of theborehole to become a part of the PRB. The portion of the boreholedesired to become a part of the PRB may then be filled with a reactivematerial comprising a solid reactant. The tube or pipe may not benecessary for installation of aspects of the PRB of the presentdisclosure.

The reactive material comprising a solid reactant can be placed in theborehole in various ways such as, conventionally or via slurry injectioninto the borehole; placing, pulling, or pushing a pre-packed cross-flowtube, packed with a reactive material comprising a solid reactant, intothe borehole; and incorporating the reactive material comprising a solidreactant into the cutting fluid.

Upon installation of a first borehole, a second borehole may made bystarting at the same location as the first borehole, thus sharing acommon head, and arcing to the desired angle prior to or after the pointat which the first borehole began to arc. This second borehole is thendirected to have a portion proximate, substantially adjacent oroverlapping the longitudinally extending portion of the first boreholeto become a part of the PRB. The portion of the second borehole tobecome a part of the PRB which is proximate, substantially adjacent oroverlapping the longitudinally extending portion of the first borehole,may have a slotted, perforated, or otherwise porous or permeable tube orpipe inserted therein and then may be filled with a reactive materialcomprising a solid reactant. This process may be repeated with a thirdborehole, fourth borehole, or any number of a plurality of boreholeshaving a substantially vertically aligned portion, proximate,overlapping, substantially adjacent, or adjacent, to achieve a desiredheight of the PRB. The height of the PRB may be measured from a lowerreactive area associated with a lower most borehole and an upperreactive area associated with an upper most borehole. Advantageously,the height of the PRB is substantially perpendicular to the direction offlow of the groundwater plume being treated.

Aspects of the present disclosure provide a permeable reactive barrierdownstream of contaminant source or groundwater plume. The PRB allowscontaminated groundwater to permeate or slowly pass therethrough whereat least a portion of the contaminants in the groundwater react with aportion of the permeable reactive barrier to produce at least oneproduct having less hazardous characteristics than at least onecontaminant in the groundwater.

Aspects of the present disclosure provide a PRB configured as anunderground porous or permeable wall with a reactive material thatreacts with or otherwise degrades contaminants in groundwater flow. Ascontaminated water passes through the reactive zone of the PRB,comprising a plurality of boreholes, each having a portionlongitudinally extending substantially parallel with an upper surface ofthe groundwater plume and substantially adjacent or overlapping anotherlongitudinally extending portion of a borehole, at least a portion ofthe contaminants are chemically degraded to a more desirable state(e.g., less toxic, more readily biodegradable, etc.). PRBs of thepresent disclosure may be installed as permanent, semi-permanent,removable, or replaceable units across the groundwater flow path of thecontaminant plume. PRBs of the present invention may incorporate afunnel-and-gate system with impermeable walls that direct thecontaminant plume through a gate to the reactive portion of the PRB.

The solid reactant in the PRB of the present disclosure may comprise avariety of reactants or combination of reactants. The solid reactant maycomprise an oxidant or oxidants, a reductant or reductants, one or morereactive materials selected from the group consisting of peroxides,permanganates, persulfates, hypochlorite solutions, ozone, zero valentiron, fluorine, sodium bisulfate, metabisulfide, polysulfide, and anycombination thereof. The solid reactant may comprise reactive materialscomprising particles substantially encapsulated with an encapsulant. Theencapsulant or encapsulate may have a characteristic selected from thegroup consisting of substantially oleophilic, hydrophobic, siliphilic,hydrocarbon soluble, and combinations thereof.

The solid reactant(s) in PRBs of at least one aspect of the presentdisclosure may be suspended solid reactant(s) and/or encapsulatedreactant(s) and may provide a means for controlling the release and/ordistribution of the reactant(s) thus providing a means for targeting acontaminant or controlling the reactivity of the reactant to minimizereaction with naturally occurring elements in the groundwater or otherbenign constituents, saving or preserving at least a portion of thereactant to react with contaminants.

The controlled release and/or distribution of the reactant(s) may bemanipulated via a suspending liquid and/or encapsulating coating whichtargets contaminants or specific organic compounds in the environmentalmedia being treated. Optionally, the reactant(s) have a coating materialthereabout providing suitable protection of the reactant for treatingthe environmental media without further encapsulation. The reactants maybe oxidants, reductants, catalysts, chelants, transition metal aminecomplexes, combinations thereof, and/or other chemical constituents thateffectuate a reaction with the targeted compounds. The reaction betweenthe encapsulated reactant(s) and the targeted organic compounds rendersat least a portion of the media being treated to have at least one lesshazardous characteristic.

A suspension having reactant(s) may be comprised of reactant particlessuspended in a liquid. The liquid may have for example water,emulsifiers, surfactants, and/or other substances as are known in theart to substantially suspend the solid reactant(s) in a suspension orslurry.

The encapsulated reactant of aspects of the present disclosure may havea single reactant contained within a single encapsulant, a plurality ofreactants contained within a single encapsulant, or a plurality ofreactants contained within a plurality of encapsulants. An outerencapsulant may provide for the targeting characteristic of theencapsulated reactant by masking, protecting, stabilizing, delaying,and/or controlling the release and/or distribution of the reactant(s)contained within. In one aspect, the outer encapsulant is substantiallyoleophilic (i.e. has a stronger affinity for oils rather than water)which may save the reactant from reacting with water or untargetedconstituents in the media being treated. Additionally, the outerencapsulant may be substantially reactive, permeable and/or dissolvablewith at least one target compound(s) being remediated. Therefore, whenthe encapsulated reactant is contacted with or exposed to thecontaminants, the coating dissolves, reacts, or absorbs at least one ofthe targeted compound(s) found in the media and exposes at least onereactant to the targeted compounds where it may react. Optionally, theencapsulated reactants may be placed in suspension or in slurry.

In another aspect of the present invention, a solid reactant may be inslurry and a liquid portion of the slurry may provide for the masking,protecting, stabilizing, delaying, and/or controlling the release and/ordistribution of the reactant(s).

An encapsulated reactant may have an organic compound in the outermostencapsulant providing an oleophilic and hydrophobic characteristics. Thereactants contained within the encapsulant may be a variety of reactantssuch as catalysts, chelants, transition metal amine complexes, oxidants,reductants, or other reactants. The encapsulated reactant of the presentinvention may be used to treat a variety of environmental media having avariety of contaminants.

Different groups of encapsulated reactants having different reactants,different coatings, and/or different outermost encapsulants can beintroduced into the same PRB or another PRB arranged upstream ordownstream, in the flow of the aquifer, of a first PRB. Suchapplications may provide a means for effectuating a single reaction ormultiple reactions, either in series or parallel toward a desired finalmedia state.

The term water as used herein refers to water in a broad sense andincorporates natural solutes. Water is considered to be a universalsolvent and has hardness, metals, and a variety of minerals and saltsnaturally dissolved and/or ionized therein. Therefore, water includessolutes except for selected contaminants and inerts. The controlledrelease and/or distribution of the reactant(s) may be manipulated viaone or more suspending liquids, coating materials, and/or anencapsulating coating to target contaminants or specific organiccompounds in the plume of contamination being treated.

The reactants may comprise oxidants, reductants, catalysts, chelants,transition metal amine complexes, combinations thereof, and/or otherconstituents that effectuate an initial, intermediate, and/or finalreaction with the organic compound(s) being treated.

Typically, in insitu remediation, the media being treated is eitherwater or has water moving within, such as soil. Therefore, reactant(s)in the PRB may be in slurry or have an outer encapsulant that issubstantially nonreacting, impermeable and/or nondissolving with water.At the same time, encapsulant or component of the slurry may be soluble,reactive, and/or permeable to at least one of the compound(s) beingtreated.

An encapsulant may be characterized by having one or more of a pluralityof mechanisms for releasing and/or contacting reactant with contaminantsin the groundwater. One mechanism in which the encapsulant may exposethe reactant to contaminants or even targeted compounds is where acontaminant or targeted organic compound permeates through theencapsulant causing an internal pressure of the encapsulated reactant toreach a level suitable for reverse osmosis, dispersing the reactant tothe zone of contamination. A second mechanism involves the encapsulantdissolving and/or rupturing with at least one contaminant or targetedorganic compound releasing the encapsulated compounds or reactants tothe zone of contamination. Additionally, a “chemical trigger” can beincorporated within an encapsulant to allow for accelerated degradationof the encapsulant and/or release of the reactant upon contact with thecontaminants or targeted compound groups being treated. The thickness,permeability, and/or composition of the encapsulant can be adjusted tocontrol the rate at which the contaminants or targeted compoundpenetrates, dissolves, and/or reacts with the encapsulant therebydistributing and/or diffusing the reactant.

One aspect of the present disclosure comprises a process for making aPRB comprising zero valent iron. Zero valent iron is a reductant whichmay function to remove chlorinated organic contaminants from thesubsurface aquifer by reductively de-chlorinating these species ascontaminated groundwater, in the plume, flows through the PRB. Zerovalent iron may be effective for remediating other halogenated organiccontaminants as well. Additionally, zero valent iron may be effective inremediating heavy metals in groundwater.

Alternatively or additionally, reactant(s) made by the process of thepresent invention may be placed in a suspension. The reactant(s) may beun-encapsulated or encapsulated. The suspending liquid can be any liquidknown in the art that provides for a suspension of solid reactant(s) inan environment to be treated and has a low oxidation or reductionpotential with the reactant(s).

The suspended, coated and/or encapsulated reactant(s) described hereinmay be produced by first grinding or comminution: media milling (ballmilling, batch milling, attritor milling, wet or dry processing, etc.);medialess milling (hammer mills, cryogenic hammer mills, jet milling,jaw crushing, high pressure dispersion milling, microfluidization,etc.); screening and/or sieving; air classification, etc. thereactant(s). The reactant(s) may then be encapsulated or coated by spraydrying and prilling; dry powder coating; melt coating, deposition, etc.Alternatively, the reactant(s) are milled in the presence of at leastone coating material to reduce reagglomeration of the reactant(s) duringmilling. Optionally, the at least one coating material provides asuitable coating of the reactant(s) for use in treating theenvironmental media without further coating or encapsulation. Theencapsulated or un-encapsulated reactant(s) may be placed in suspensionor in slurry prior to placing into the environment to be treated.

In at least one embodiment of the instant disclosure, at least one solidreactant is contained within a solid coating or encapsulating materialsuch as a wax. For example, solid blocks, slabs, or other shaped massesof encapsulating material(s) and reactant(s) may be placed into theboreholes. These masses may be size reduced, by chipping, for example,prior to feeding into a borehole. These chips or reduced sized masses ofencapsulating material(s) and reactant(s) may be put into a suspension,allowing them to flow into the borehole.

In at least one other embodiment, sheets or slabs of encapsulatingmaterial(s) and reactant(s) may be substantially impermeable to theflowing groundwater and may be placed directly into the subsurface todivert the flow of the groundwater to a PRB. For example, in a funneland gate system, as is known in the art, the funnels may comprise sheetsor slabs of encapsulating material(s) and reactant(s) and the gate maycomprise a PRB.

Certain exemplary embodiments can provide a treatment technique for anyand/or all of the above listed chemical contaminant(s) within a varietyof medias and/or subterranean environments comprising: silts, clays,sands, fractured bedrock, karsts, organics, and/or tills. Via certainexemplary embodiments, in situ environmental remediation withinsubsurface bedrock and/or fractured bedrock networks can be greatlyincreased due to the above mentioned adjustable properties of theparticle and/or aqueous mixture.

A PRB may be installed down flow of a plume of contamination in theaquifer and filled with a reactive material comprising at least onesolid reactant. In this application, the reactant(s) may be pure orsubstantially pure, in a suspending liquid, coated, and/or have an outerencapsulant. The suspending liquid, coating, and/or encapsulant may bedesigned to remain un-reacted or intact for an extended period of time(e.g. years) and as the plume of contamination passes through the PRB,the encapsulant may allow targeted constituents to react with thereactant(s). A reactive oxidant may be kept segregated from a metallicsalt(s), chelate(s), and/or buffering agent(s) by internalencapsulation, hence deferring any intermediate reaction there between.Once the desired time or condition of exposure to an aqueous environmenthas elapsed and/or a “triggered” exposure to the contaminant(s) ofconcern has occurred, an outer encapsulant can release the oxidant intothe presence of the metallic salt(s), chelate(s), and/or bufferingagent(s), allowing any intermediate reaction there between to occur, andthereby resulting in the production of oxidizing free radicals, hydroxylradicals, sulfate radicals, or the like possibly by virtue of a mimickedFenton's reaction. The radicals can undergo a final reaction with thecontaminant(s) of concern, oxidizing the contaminant compound(s)(typically exothermically), often times into final products of carbondioxide and water.

The method of using products made by the method of the present inventionmay utilize a combination of one or more reactants. The reactant(s) maybe applied directly, suspended, coated, and/or encapsulated. Thereactant(s) may comprise oxidant(s), reductant(s), metallic saltcatalyst(s), and/or chelating agent(s) under conditions which enableoxidation or reduction of most, and preferably substantially all,volatile, semi-volatile, or non-volatile organic and/or inorganiccompounds such as heavy metals in soil, rock, sludge, water,groundwater, and/or wastewater rendering them less harmful.

In one embodiment of the present invention, a combination of oxidant(s)(a persulfate group—potassium or sodium), catalyst(s) (iron salt), andchelating compound(s) (EDTA), encapsulated or unencapsulated, are placedinto a PRB simultaneously within an aqueous mixture, slurry, orsuspension. For instance, a combination of suspended reactant(s), mayinclude a first group of suspended, free, coated, and/or encapsulatedreactants having persulfate and a second group of suspended, free,coated and/or encapsulated reactants having ferrous sulfate. Thesuspended, free, coated and/or encapsulated reactants may remainsubstantially unreactive within the subsurface until contact with acontaminant occurs. Upon contact, the suspending liquids, coatings,and/or encapsulants about the reactants may begin to degrade, weaken, orbecome more permeable until the reactant contacts the contaminant(s).The oxidant and/or catalyst and/or chelating agent react independentlyor in combination, resulting ultimately in the partial or completeoxidation of the contaminant(s). The final by-products of the oxidationreaction are typically carbon dioxide, water, a salt group (depending onoxidant of choice), and an inorganic chloride ion (if contaminant ischlorinated).

In at least one embodiment of the present invention, a reduced sizereactant particle, un-encapsulated or encapsulated, are placed insuspension or slurry, several advantages may be realized. The slurriesor suspensions of the reduced sized reactant particles may serve toovercome a low solubility of the reactant(s). For example, the PRB maybe filled with a concentrated suspension or slurry, thereby minimizingthe total fluid volume required for treatment application. For example,potassium permanganate has a solubility of about 4% by weight in water.The concentration of the reactant(s) in the slurry may be increased byusing different suspending fluids or by adding surfactants, emulsifiers,or polymeric materials to water to form a suspending liquid, forexample. The concentration of the reactant in suspension may beincreased to 25%, 50%, or even more. This increase in reactantconcentration in suspension may reduce the volume of the PRB and thevolume of the suspension to be injected or placed in the in situenvironment.

In at least one embodiment of the present invention, a reactant havingsodium persulfate and optionally a catalyst, e.g. one or more metallicsalts, may be contained within an encapsulant having cellulose, wax,polylactic acid, or combinations or derivatives thereof. Such anembodiment may provide persistence of the reactant(s) in water until theencapsulated reactants encounter contaminants at which point thereactant(s) break down at least one contaminant rendering it lessharmful.

The outer coating and/or encapsulant surrounding the reactant(s) may bedesigned to delay the chemical reaction between reactant and targetedcontaminant(s) to allow for an extended coverage area and/or time whenapplied to subsurface treatment. Additionally, the size of theencapsulated reactant can be preselected to allow for less restrictedflow through the subterranean environment, and thereby can provide forextended coverage areas and/or reduced loading restrictions.

Another aspect of the present invention uses reduced sized reactantparticles. A coating material that is advantageously substantiallyoleophilic, hydrophobic, siliphilic, hydrocarbon soluble, or exhibits acombination of these properties, the coating material continuouslysubstantially coats the oxidant particles. The particles mayadvantageously have a mean diameter of at most 100 μm, moreadvantageously of at most 10 μm, even more advantageously at most 5 μm,and most advantageously at most 1 μm.

Yet another aspect of the present invention uses larger sized reactantparticles and/or larger sized encapsulating or coating materialcontaining a plurality of larger or reduced sized solid reactantparticles. For example, a coating material, such as a wax, may be of alarge mass and may comprise a plurality of reactant particles. Thereactant particles may have a mean diameter greater than or less than100 μm. The coating material comprising the reactant may be reduced insize, chipping for example, and placed in suspension prior to injectinginto the borehole.

A coating material or component of a suspension may be an oil or wax andmay be derived from animals, hydrocarbons, vegetables, silicones, or anycombinations thereof. For example, the coating material may be a waxsuch as paraffin. Optionally, a coating material is a combination ofoils, waxes, or oils and waxes. The small particle size of the oxidantparticles may make them suitable for holding in a suspension that may beapplied directly into the environment to be treated. The optionallyprovided substantially hydrophobic and substantially oleophilic outerencapsulant in the encapsulated reactants of embodiments of the instantinvention may provide a means to control the release of reactant(s)until contact occurs with the targeted contaminants. This may provide ahighly efficient contaminant destruction ratio using lesser amounts ofoxidant(s), catalyst(s), chelating agents and/or other reactants. Areasof influence, both horizontally and vertically, from point ofapplication or injection may be increased. The reactants may providemore capability of controlling the reactant's path of travel or distancesince the properties of the coating material, suspending fluid, and/orouter encapsulant may be modified. The reactant's size, surface area,buoyancy, specific gravity, density, etc. may be manipulated to engineerencapsulated reactant(s) to float, suspend, or sink within thesubsurface providing an increased means of reaching targetedcontaminants.

FIG. 1 shows directional drill rig 10 and a portion of a permeablereactive barrier 29 made therewith. Directional drill rig 10 ispositioned upon soil surface 12 at a desired angle of incidence of adrill head. Directly below soil surface 12 is a vadose zone 24, which isan unsaturated zone extending from soil surface 12 to aquifer 16.Between aquifer 16 and vadose zone 24 may be a partially saturated zone26 that may become substantially saturated from the rising and loweringof the water table or aquifer 16 and/or through capillary action.

In at least one embodiment, PRB 29 is in a plane substantiallyperpendicular to the direction of flow of water in aquifer 16. PRB 29may be made by drilling or cutting into soil 24 at well head 20.Drilling may be continued at an angle proximate to an angle of entryuntil the borehole becomes proximate a contamination plume where it maybe leveled off or arced to become substantially parallel to surface 28of aquifer 16. This area of contamination is generally designated withvertical line “A” and extending in the direction designated with “B”.The zone designated as 18 is below the area of aquifer 16 to be treatedwith PRB 29. Zone 18 may be bedrock, an area of aquifer 16 having alower flow rate, an area of aquifer 16 having a low concentration ofcontamination, or an area of aquifer 16 that is not be treated with PRB29.

Upon becoming proximate the plume of contamination to be treated,designated generally with “A” and “B”, the borehole is substantiallyleveled off to make a portion longitudinally extending substantiallyparallel with an upper surface 28 of the groundwater plume, asdesignated by 22(a)-22(i). In at least one embodiment, eachlongitudinally portion of each bore hole, 22(a)-22(i), is formed bydrilling through a common well head 20. For example, a first boreholehaving longitudinal portion 22(a) may be made and the drill head may beretracted to the portion of the drill head 23 having each borehole22(a)-22(i) extending thereform. A second borehole may then arc awayfrom longitudinal portion 22(a) to form longitudinal portion 22(b). Thisprocess may be repeated for each portion, 22(a)-22(i), longitudinallyextending substantially parallel with upper surface 28 of thegroundwater plume 16, until a desired height of PRB 29 is obtained. Inat least one embodiment of the present disclosure, boreholes 22(a)-22(i)are substantially adjacent or adjacent within acceptable tolerances. Inat least one other embodiment of the present disclosure, boreholes22(a)-22(i) are substantially vertically aligned or vertically alignedwithin acceptable tolerances.

FIGS. 2A and 2B show examples of drill heads that may be used in atleast one embodiment of the present disclosure. FIG. 2A shows a duckbilldrill head 30 having duckbill 34 angularly extending from an end ofdrill rod 32. FIG. 2B shows a rotary drill head 35 having protrusions 36extending outward from a conical end. Drill head 35 may have an open end38 for the flow of drilling or cutting fluids. Protrusions 36 and/or theend of drill head 35 about open end 38 may be designed for cutting soilor rock.

Some examples of permeable reactive barriers, which may be used oradapted for use in at least one possible embodiment of the presentdisclosure, may be found in the following U.S. patents: U.S. Pat. No.6,254,786 to Carpenter et al., U.S. Pat. No. 6,428,695 to Naftz et al.,and U.S. Pat. No. 7,217,755 to Harrup, Mason K.

Some examples of reactants, which may be used or adapted for use in atleast one possible embodiment of the present disclosure, may be found inthe following U.S. Patents and Publications: US20080275288 to Swearenginet al., U.S. Pat. No. 7,431,849 to Swearengin et al., and US20090061082to Swearengin et al.

The purpose of incorporating U.S. patents, foreign patents,publications, etc. is solely to provide additional information relatingto technical features of one or more embodiments, which information maynot be completely disclosed in the wording in the pages of thisapplication. However, words relating to the opinions and judgments ofthe author and not directly relating to the technical details of thedescription of the embodiments therein are not incorporated byreference. The words all, always, absolutely, consistently, preferably,guarantee, particularly, constantly, ensure, necessarily, immediately,endlessly, avoid, exactly, continually, expediently, ideal, need, must,only, perpetual, precise, perfect, require, requisite, simultaneous,total, unavoidable, and unnecessary, or words substantially equivalentto the above-mentioned words in this sentence, when not used to describetechnical features of one or more embodiments of the patents, patentapplications, and patent publications, are not considered to beincorporated by reference herein.

The invention claimed is:
 1. A process for insitu treatment of at leastone contaminant in a groundwater plume, the process consists essentiallyof the steps of: installing a permeable reactive barrier configured anddisposed to intercept the migration of at least one groundwatercontaminant in the groundwater plume, wherein the installation of thepermeable reactive barrier consists essentially of the steps of: boringa first borehole with a portion longitudinally extending substantiallyparallel with an upper surface of the groundwater, the first boreholebeing bored with a duckbill or rotary drill head; filling thelongitudinally extending portion of the first borehole with a reactivematerial comprising a solid reactant configured to react with the atleast one contaminant in the groundwater plume to produce at least oneproduct having less hazardous characteristics than the at least onecontaminant; boring a second borehole with a portion substantiallyparallel with the upper surface of the groundwater, the second boreholebeing bored with a duckbill or rotary drill head; and filling thelongitudinally extending portion of the second borehole with thereactive material comprising a solid reactant configured to react withthe at least one contaminant in the groundwater plume to produce atleast one product having less hazardous characteristics than the atleast one contaminant; passing at least a portion of the at least onecontaminant through a portion of the permeable reactive barrier; andreacting at least a portion of the at least one contaminant with aportion of the permeable reactive barrier to produce at least oneproduct having less hazardous characteristics than the at least onecontaminant.
 2. The process for insitu treatment of at least onecontaminant in a groundwater plume of claim 1 wherein the longitudinallyextending portion of the first and second boreholes are disposedsubstantially in a common plane.
 3. The process for insitu treatment ofat least one contaminant in a groundwater plume of claim 1 wherein thelongitudinally extending portion of the first and second boreholes aredisposed substantially parallel with each other.
 4. The process forinsitu treatment of at least one contaminant in a groundwater plume ofclaim 1 wherein said step of boring a first borehole and said step ofboring a second borehole are performed by directional drilling.
 5. Aprocess for insitu treatment of at least one contaminant in agroundwater plume, the process consisting essentially of the steps of:installing a permeable reactive barrier configured and disposed tointercept the migration of at least one groundwater contaminant, whereinthe installation of the permeable reactive barrier consists essentiallyof the steps of: boring a first borehole with a portion longitudinallyextending substantially parallel with an upper surface of thegroundwater and being bored with a duckbill or rotary drill head;filling the longitudinally extending portion of the first borehole witha reactive material comprising a solid reactant configured to react withthe at least one contaminant in the groundwater plume to produce atleast one product having less hazardous characteristics than the atleast one contaminant; boring a second borehole with a portionsubstantially parallel to the longitudinally extending portion of thefirst borehole and being bored with a duckbill or rotary drill head;filling the portion of the second borehole substantially parallel to thelongitudinally extending portion of the first borehole with the reactivematerial; intercepting at least a portion of the at least onecontaminant with the permeable reactive barrier; and reacting at least aportion of the at least one contaminant with a portion of the permeablereactive barrier to produce at least one product having less hazardouscharacteristics than the at least one contaminant.
 6. The process forinsitu treatment of at least one contaminant in a groundwater plume ofclaim 5 wherein the longitudinally extending portion of the first andsecond boreholes are disposed substantially in a common plane.
 7. Theprocess for insitu treatment of at least one contaminant in agroundwater plume of claim 6 wherein the longitudinally extendingportion of the first and second boreholes are disposed substantially ina common vertical plane.
 8. The process for insitu treatment of at leastone contaminant in a groundwater plume of claim 5 comprising at leastone of a)-f), wherein a)-f) are: a) said reactive material comprises anoxidant or a reductant; b) said reactive material comprises at least oneof: peroxides, permanganates, persulfates, hypochlorite solutions,ozone, zero valent iron, fluorine, sodium bisulfate, metabisulfide, andpolysulfides; c) said reactive material comprises particlessubstantially encapsulated with an encapsulant having a characteristicselected from the group consisting of substantially oleophilic,hydrophobic, siliphilic, hydrocarbon soluble, and combinations thereof;d) said reactive material comprises one or more catalysts, chelants,transition metal amine complexes, and other constituents that effectuatean initial, intermediate, or final reaction with an organic compound; e)the at least one contaminant comprises at least one metal contaminant;and f) the at least one contaminant comprises at least one targetedorganic compound.
 9. The process for insitu treatment of at least onecontaminant in a groundwater plume of claim 5 wherein said step ofboring a first borehole and said step of boring a second borehole areperformed by directional drilling.
 10. A process for insitu treatment ofat least one contaminant in a groundwater plume consisting essentiallyof the steps of: installing a permeable reactive barrier configured anddisposed to intercept the migration of at least one groundwatercontaminant, wherein the installation of the permeable reactive barrierconsists essentially of the steps of: directionally drilling a firstborehole with a duckbill or rotary drill head; filling at least aportion of the first borehole with a reactive material comprising asolid reactant configured to react with the at least one contaminant inthe groundwater plume to produce at least one product having lesshazardous characteristics than the at least one contaminant;directionally drilling a second borehole with a duckbill or rotary drillhead; said steps of directionally drilling the first and secondboreholes consist essentially of drilling a portion longitudinallyextending substantially parallel with an upper surface of thegroundwater and transmitting a signal from proximate a drill bit andreceiving the transmitted signal with a receiver positioned above thesurface of the ground and steering the drill bit in response to thereceived signal; and filling at least a portion of the second boreholewith a reactive material comprising a solid reactant configured to reactwith the at least one contaminant in the groundwater plume to produce atleast one product having less hazardous characteristics than the atleast one contaminant; intercepting at least a portion of the at leastone contaminant with the permeable reactive barrier; and reacting atleast a portion of the at least one contaminant with a portion of thepermeable reactive barrier to produce at least one product having lesshazardous characteristics than the at least one contaminant.
 11. Theprocess for insitu treatment of at least one contaminant in agroundwater plume of claim 10 wherein said first borehole and saidsecond borehole each have a longitudinally extending portion disposedsubstantially in a common plane.
 12. The process for insitu treatment ofat least one contaminant in a groundwater plume of claim 11 wherein saidfirst borehole and said second borehole each have a longitudinallyextending portion disposed substantially in a common vertical plane. 13.The process for insitu treatment of at least one contaminant in agroundwater plume of claim 10 wherein the longitudinally extendingportion of the second borehole is substantially parallel to thelongitudinally extending portion of the first borehole.
 14. The processfor insitu treatment of at least one contaminant in a groundwater plumeof claim 10 wherein the longitudinally extending portion of the secondborehole is proximate to the longitudinally extending portion of thefirst borehole.
 15. The process for insitu treatment of at least onecontaminant in a groundwater plume of claim 10 wherein said reactivematerial comprises one or more oxidants, reductants, catalysts,chelants, transition metal amine complexes, and other constituents thateffectuate an initial, intermediate, or final reaction with an organiccompound.
 16. The process for insitu treatment of at least onecontaminant in a groundwater plume of claim 10 wherein: said step offilling at least a portion of the first borehole with a reactivematerial with a reactive material and said step of filling at least aportion of the second borehole with a reactive material is performed byinserting a tube or pipe configured to permit flow of water through acircumferential surface thereof, said tube or pipe containing saidreactive material.